Expansible wheel



(No Model.) 2 Sheets-Sheet 1.

D. E. ROSS. BXPANSIBLB WHEEL.

No. 577,323. Patented Feb. 16,1897.

l L lu/v D. E. ROSS.

EXPANSIBLE WHEEL.

Patented Feb. 16, 1897.

side view of a driving-sprocket having a sec- DAVID E. ROSS, OF BROOKSTON, INDIANA.

EXPANSIBLE WHEEL.

SPECIFICATION forming part of Letters Patent No. 577,323, dated Februaryv 16, 1897.

Application tiled January 30, 1896.

To o//ZZ whom 7215 may concern:

Be it known that I, DAVID E. Ross, of Brookston, in the county of IVhite and Stat-e of Indiana, have invented certain new and useful Improvements in Expansible Wheels; and I do hereby declare that the following is a full, clear, and exact description thereof, reference being had to the accompanying drawings, and to the letters of reference marked thereon,which form part of this speciiication.

This invention is an improvement in pulleys and sprocket-wheels; and its object is to so construct the same that they can be varied in size to a limited extent, and thus increase or diminish the power transferred by or imparted thereto by belts or chains. It is especiallydesigned for sprocket-wheels of bicycles, where it is sometimes desirable to increase the speed by increasing the size of the driving-sprocket or decreasing the size of the driven sprocket, or to increase the power by decreasing the size of the driving-sprocket or increasing the size of the driven sprocket. I propose to make both sprockets adjustable, and by expanding one in proportion as the other is contracted be able to considerably vary the power transmitted from one to the other with little trouble, and also avoid the necessity for any chain compensating or tautening device.

In the drawings I have shown several sprockets embodying the principle of my invention, which is best summarized in the claims, and Iwill proceed with the description thereof.

Referring to said drawings, Figure l is a tional split rim, showing it expanded in dotted lines and contracted in full lines. Fig. 2 is a similar view of the driven sprocket, showing it expanded in dotted lines and contracted in full lines. Fig. 3 is a section on line 3 3, Fig. l; Fig. 4, a section on line 4 4, Fig. 2. Figs. 5 and 6 are details. Fig. 7 is a detail view. of a sprocket having one-piece split continuons rim. Fig. S is a detail.

The drioingsproctetAs shown in Fig. l, the split rim of the sprocket is composed of six sprocket-toothed segments A, hinged together. The two sections A A2,between which is the split,7 instead of being connected by Serial No. 577,456. (No model.)

AWhen the rim is contracted so as to cause sections Al A2 to abut, the adjoining teeth thereon are just the proper distance apart; but when the rim is expanded sections A A2 separate until their adjoining end teeth are separated by a space sufficient to admit of another tooth, if desired. I do not think it essential to provide this tooth, though it can easilybe formed,forinstance,upon the tongue a', if desired, and telescope with the end tooth on section A2 when the rim is contracted. The pins a by which the several sections A are hinged together pass through slot-s b in the extremities of spokes B, on a hub or web B, as shown, the extremities of spokes B being preferably bifurcated, so as to partially embrace the rim and support the pins on both sides of the segments. (See Fig. 8.) The slots b are so formed as to allow the sections to accommodate for expansion or contraction of the rim while remaining concentric to the axis of the wheel.

' C O are lever-arms, the inner ends of which are pivoted at c c to the hub B. The outer end of lever C is pivoted to an inwardly-projecting lug c on the tongue a by a pin d, and the outer end of lever C is pivoted to a corresponding lug c2 on the segment A2 by a pin d. 4 A link D is pivoted on pin d and a short link D is pivoted on pin d. The links D D are also pivoted together, as at D2, and the pivot-pin D2 is extended and bent to form a short lever D3 by which link D can be turned. When links D D' lie end to end, as in full lines, Fig. 5, the rim is circumferentially expanded, but when link D is turned around under link D the rim is circumferentially contracted. The links may be locked in either position by engaging the end of lever Dwith retaining lugs or notches d4 d5 on segments A A2. The pivot-pins d, d', and D2 stand in line when the rim is fully expanded or contracted, and this eifectually prevents casual shifting of the rim. This adjusting IOO device is very powerful and positive, but I do not consider it essential to the invention that segmental rims be used. In Fig. 7 the rim is made of one piece of resilient metal and expanded or contracted by means of the links D D, rbc., as above described. Therefore I do not coniine myself to segmental rims. For convenience link D may be split at one end, soit can be sprung on pin D2, the split being closed by a nut or screw d'1.

The dri/uen sprocket-The driven sprocket is constructed substantially like the drivingsprocket except that a less number of segments are employed, and instead of the hub and sprocket the rim is inclosed between two side plates E E, which are slotted, as at e e, to receive the ends of the hinge-pins a of the segments. The plates E E are connected firmly by transverse bolts F, passing through sleeves j". The small sprocket is expanded or contracted like the larger, and as similar letters of reference designate like parts in all the figures the foregoing description of the operation of expanding or contracting the larger wheel applies to the others also. It is to be noted, however, that no levers C C are employed in the small sprocket, Fig. 2, as they are unnecessary, the links D D being pivoted solely to the lugs c' c2. The same is true of Fig. 7, where the continuous rim is used, but in that iigure the hub I3 is provided with spokes B2 to support the segments A A2 like the others are supported. In Fig. l the levers C C take the place of spokes B2.

It will be readily understood that the invention is not limited to sprocket-wheels, but is applicable to pulleys, the.

lVhen used on a bicycle, I propose to make both driving and driven sprockets adjustable. Then by contracting the driven sprocket one tooth when the driving-sprocket is expanded one tooth I maintain a proper tension on the chain and do not require any slack-take-up device therefor. The adjustment can be made easily by hand by simply swinging levers I)3 around one hundred and eighty degrees.

Having thus described my invention, what I claim as new, and desire to secure by Letters Patent thereon, is-

l. In an expansiblc sprocket, the combination of a toothed split rim, a hub provided with rigid spokes attached to the rim by slots and pins, and means for simultaneously and uniformly expanding or contracting the rim, by distending or closing the split therein and locking the rim when it is expanded or contracted, substantially as and for the purpose described.

2. The combination of the split rim composed of a series of segments hinged together at their ends, a hub having rigid spokes loosely attached to the segments, and supporting them upon the hub, and means for simultaneously and uniformly expanding or contracting the rim by distending or closing the joint between two of its segments, substantially as described.

3. In an expansible pulley or wheel, the combination of a split rim, with a pair ot links respectively connected to the rim on the opposite ends of the rim, and to each other, and means for partially rotating one of said links, whereby the split is closed or distendcd and the rim contracted or expanded, substantially as described.

et. In an expansible pulley or wheel, the combination of the rim split at one side, and having inwardly-projecting lugs en its ends on opposite sides of the split, with the links pivoted to opposite lugs and to each other, one of said links being shorter than the other, and means for turning the shorter link, substantially as described.

5. In an expansiblc pulley or wheel, the combination of a split rim, with a pair of links respectivelyconnected to the rim on the opposite ends of the rim, and to each other, and means for partially rotating one of said links, whereby the split is closed or distended and the rim contracted or expanded, and supports for the rim connected thereto so as to admit of the expansion or contraction thereof, substantially as described.

G. In a pulley the combination of the split rim having lugs c', c2, on opposite sides of the split, the link D pivoted to lug c', the short link D' pivoted to lug c2, and to lug D, and having a lever D3, substantially as described.

7. The combination of the hub having spokes provided with slotted ends; a split rim having pins engaging the slots in the spokes, the links connecting` the split ends of the rim, and means for shifting said links so as to eX- pand or contract the rim, substantially as described.

8. The combination of the split rim composed of segments hinged together, the links D, D', pivoted to the opposite segments at the split of the rim, and also pivoted to each other, and means for turning one of said links so as to distend or close the split in the rim, substantially as described.

f). The herein-described sprocket, consisting of toothed segments A, and segments A', A2, the hub B, having bifurcated and slotted spokes B the levers C pivoted to hub B, and respectively pivoted to a lug c on segment A' and lug c2 on segment A2, the link D pivoted to lug c', and link D' pivoted to lug c2, said links being pivoted together, and the lever D3 for turning and locking link D', all substantially as and for the purpose set forth.

In testimony that I claim the forcgoin g as my own I affix my signature in presence of two witnesses.

DAVID E. ROSS.

IVitnesses:

JAMES HAY, Levi MYERS.

IOD

IOS 

